Two-level led security light with motion sensor

ABSTRACT

A method of configuring an LED light with a tunable diffused light color temperature is disclosed. The method comprises using a light-emitting unit configured with a first LED load emitting light with a low color temperature and a second LED load emitting light with a high color temperature electrically connected in parallel, using a light diffuser to cover the first LED load and the second LED load to create a diffused light with a diffused light color temperature, using two semiconductor switching devices working in conjunction with a controller to respectively control a first electric power delivered to the first LED load and the second electric power delivered to the second LED load to operate a color temperature tuning and switching scheme and using a first external control device to output at least one first external control signal to activate a selection of a diffused light color temperature.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of application Ser. No. 16/244,671, filed Jan.10, 2019. Ser. No. 16/244,671 is a continuation of application Ser. No.15/896,403, filed Feb. 14, 2018, which issued as U.S. Pat. No.10,225,902 on Mar. 5, 2019. U.S. Pat. No. 10,225,902 is a continuationof application Ser. No. 15/785,658, filed Oct. 17, 2017, which issued asU.S. Pat. No. 10,326,301 on Jun. 18, 2019. U.S. Pat. No. 10,326,301 is acontinuation of application Ser. No. 15/375,777, filed Dec. 12, 2016,which issued as U.S. Pat. No. 9,826,590 on Nov. 21, 2017. U.S. Pat. No.9,826,590 is a continuation of application Ser. No. 14/836,000, filedAug. 26, 2015, which issued as U.S. Pat. No. 9,622,325 on Apr. 11, 2017.U.S. Pat. No. 9,622,325 is a divisional of application Ser. No.14/478,150, filed Sep. 5, 2014, which issued as U.S. Pat. No. 9,445,474on Sep. 13, 2016. U.S. Pat. No. 9,445,474 is a continuation ofapplication Ser. No. 13/222,090, filed Aug. 31, 2011, which issued asU.S. Pat. No. 8,866,392 on Oct. 21, 2014.

BACKGROUND OF THE INVENTION 1. Technical Field

The present disclosure relates to a lighting apparatus, in particular,to a two-level security LED light with motion sensor

2. Description of Related Art

Lighting sources such as the fluorescent lamps, the incandescent lamps,the halogen lamps, and the light-emitting diodes (LED) are commonlyfound in lighting apparatuses for illumination purpose. Photoresistorsare often utilized in outdoor lighting applications for automaticilluminations, known as the Photo-Control (PC) mode. Timers may be usedin the PC mode for turning off the illumination or for switching to alower level illumination of a lighting source after the lighting sourcehaving delivered a high level illumination for a predetermined duration,referred as the Power-Saving (PS) mode. Motion sensors are often used inthe lighting apparatus for delivering full-power illumination thereoffor a short duration when a human motion is detected, then switchingback to the PS mode. Illumination operation controls such asauto-illumination in accordance to the background brightness detection,illumination using timer, illumination operation control using motionsensing results (e.g., dark or low luminous power to fully illuminated),and brightness control are often implemented by complex circuitries. Inparticular, the design and construction of LED drivers are still of acomplex technology with high fabrication cost.

Therefore, how to develop a simple and effective design method onillumination controls such as enhancing contrast in illumination andcolor temperature for various types lighting sources, especially thecontrols for LEDs are the topics of the present disclosure.

SUMMARY OF THE INVENTION

An exemplary embodiment of the present disclosure provides a two-levelLED security light with motion sensor which may switch to high levelillumination in the Power-Saving (PS) mode for a predetermined durationtime when a human motion is detected thereby achieve warning purposeusing method of electric current or lighting load adjustment.Furthermore, prior to the detection of an intrusion, the LED securitylight may be constantly in the low level illumination to save energy.

An exemplary embodiment of the present disclosure provides a two-levelLED security light including a power supply unit, a light sensingcontrol unit, a motion sensing unit, a loading and power control unit,and a light-emitting unit. The light-emitting unit further includes oneor a plurality of series-connected LEDs; when the light sensing controlunit detects that the ambient light is lower than a predetermined value,the loading and power control unit turns on the light-emitting unit togenerate a high level or a low level illumination; when the lightsensing control unit detects that the ambient light is higher than thepredetermined value, the loading and power control unit turns off thelight-emitting unit; when the motion sensing unit detects a human motionin the PS mode, the loading and power control unit increases theelectric current that flows through the light-emitting unit so as togenerate the high level illumination for a predetermined duration.

Another exemplary embodiment of the present disclosure provides atwo-level LED security light including a power supply unit, a lightsensing control unit, a motion sensing unit, a loading and power controlunit, a light-emitting unit. The light-emitting unit includes aplurality of series-connected LEDs. When the light sensing control unitdetects that the ambient light is lower than a predetermined value, theloading and power control unit turns on a portion or all the LEDs of thelight-emitting unit to generate a low level or a high levelillumination; when the light sensing control unit detects that theambient light is higher than the predetermined value, the loading andpower control unit turns off all the LEDs in the light-emitting unit;when the motion sensing unit detects a human motion in the PS mode, theloading and power control unit turns on a plurality of LEDs in thelight-emitting unit and generates the high level illumination for apredetermine duration. An electric current control circuit is integratedin the exemplary embodiment for providing constant electric current todrive the LEDS in the light-emitting unit.

One exemplary embodiment of the present disclosure provides a two-levelLED security light including a power supply unit, a light sensingcontrol unit, a motion sensing unit, a loading and power control unit,and a light-emitting unit. The light-emitting unit includes a phasecontroller and one or a plurality of parallel-connected alternatingcurrent (AC)LEDs. The phase controller is coupled between the describedone or a plurality parallel-connected ACLEDs and AC power source. Theloading and power control unit may through the phase controller controlthe average power of the light-emitting unit; when the light sensingcontrol unit detects that the ambient light is lower than apredetermined value, the loading and power control unit turns on thelight-emitting unit to generate a high level or a lower levelillumination; when the light sensing control unit detects that theambient light is higher than the predetermined value, the loading andpower control unit turns off the light-emitting unit; when the motionsensing unit detects a human motion in the PS mode, the loading andpower control unit increases the average power of the light-emittingunit thereby generates the high level illumination for a predetermineduration.

According to an exemplary embodiment of the present disclosure, atwo-level LED security light includes a power supply unit, a lightsensing control unit, a motion sensing unit, a loading and power controlunit, and a light-emitting unit. The light-emitting unit includes X highwattage ACLEDs and Y low wattage ACLEDs connected in parallel. When thelight sensing control unit detects that the ambient light is lower thana predetermined value, the loading and power control unit turns on theplurality of low wattage ACLEDs to generate a low level illumination;when the light sensing control unit detects that the ambient light ishigher than a predetermined value, the loading and power control unitturns off the light-emitting unit; when the motion sensor detects anintrusion, the loading and power control unit turns on both the highwattage ACLEDs and the low wattage ACLEDs at same time thereby generatesa high level illumination for a predetermine duration, wherein X and Yare of positive integers.

According to an exemplary embodiment of the present disclosure, atwo-level LED security light with motion sensor includes a power supplyunit, a light sensing control unit, a motion sensing unit, a loading andpower control unit, and a light-emitting unit. The light-emitting unitincludes a rectifier circuit connected between one or a plurality ofparallel-connected AC lighting sources and AC power source. The loadingand power control unit may through the rectifier circuit adjust theaverage power of the light-emitting unit. When the light sensing controlunit detects that the ambient light is lower than a predetermined value,the loading and power control unit turns on the light-emitting unit togenerate a low level illumination; when the light sensing control unitdetects that the ambient light is higher than the predetermined value,the loading and power control unit turns off the light-emitting unit;when the motion sensing unit detects an intrusion, the loading and powercontrol unit increases the average power of the light-emitting unitthereby generates a high level illumination for a predetermine duration.The rectifier circuit includes a switch parallel-connected with a diode,wherein the switch is controlled by the loading and power control unit.

To sum up, a two-level LED security light with motion sensor provided byan exemplary embodiment in the preset disclosure, may executePhoto-Control (PC) and Power-Saving (PS) modes. When operates in the PCmode, the lighting apparatus may auto-illuminate at night andauto-turnoff at dawn. The PC mode may generate a high level illuminationfor a predetermined duration then automatically switch to the PS mode bya control unit to generate a low level illumination. When the motionsensor detects a human motion, the disclosed LED security light mayimmediate switch to the high level illumination for a shortpredetermined duration thereby achieve illumination or warning effect.After the short predetermined duration, the LED security light mayautomatically return to the low level illumination for saving energy.

In order to further understand the techniques, means and effects of thepresent disclosure, the following detailed descriptions and appendeddrawings are hereby referred, such that, through which, the purposes,features and aspects of the present disclosure can be thoroughly andconcretely appreciated; however, the appended drawings are merelyprovided for reference and illustration, without any intention to beused for limiting the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the present disclosure, and are incorporated in andconstitute a part of this specification. The drawings illustrateexemplary embodiments of the present disclosure and, together with thedescription, serve to explain the principles of the present disclosure.

FIG. 1 schematically illustrates a block diagram of a two-level LEDsecurity light in accordance with an exemplary embodiment of the presentdisclosure.

FIG. 1A is an enhanced block diagrammed under FIG. 1 to specificallyillustrate an embodiment of FIG. 1 for an AC LED two-level securitylight, wherein the loading and power comprises a switching circuitry anda microcontroller, wherein the switching circuitry further comprises abidirectional semiconductor switching device for controlling an averageelectric power to be delivered to the AC LED.

FIG. 1B is an enhanced block diagrammed under FIG. 1 to specificallyillustrate an embodiment of FIG. 1 for a DC LED two-level securitylight, wherein the loading and power control unit comprises a switchingcircuitry and a microcontroller, wherein the switching circuitry furthercomprises an unidirectional semiconductor switching device forcontrolling an average electric power to be delivered to the DC LED.

FIG. 1C is an enhanced block diagrammed under FIG. 1 to specificallyillustrate an embodiment of FIG. 1 for a AC LED two-level security lightincluding a first set having N number LEDs and a second set having Mnumber LEDs, wherein the loading and power control unit comprises aswitching circuitry and a microcontroller, wherein the switchingcircuitry further comprises bidirectional semiconductor switchingdevices for controlling an average electric power to be delivered to theAC LED.

FIG. 1D is an enhanced block diagrammed under FIG. 1 to specificallyillustrate an embodiment of FIG. 1 for a DC LED two-level security lightincluding a first set having N number LEDs and a second set having Mnumber LEDs, wherein the loading and power control unit comprises aswitching circuitry and a microcontroller, wherein the switchingcircuitry further comprises unidirectional semiconductor switchingdevices for controlling an average electric power to be delivered to theDC LED.

FIG. 2A illustrates a schematic diagram of a two-level LED securitylight in accordance to the first exemplary embodiment of the presentdisclosure.

FIG. 2B graphically illustrates a timing waveform of a pulse widthmodulation (PWM) signal in accordance to the first exemplary embodimentof the present disclosure.

FIG. 3A illustrates a schematic diagram of a two-level LED securitylight in accordance to the second exemplary embodiment of the presentdisclosure.

FIG. 3B illustrates a schematic diagram of a two-level LED securitylight in accordance to the second exemplary embodiment of the presentdisclosure.

FIG. 4A illustrates a schematic diagram of a two-level LED securitylight in accordance to the third exemplary embodiment of the presentdisclosure.

FIG. 4B illustrates a timing waveform of two-level LED security light inaccordance to the third exemplary embodiment of the present disclosure.

FIG. 5 illustrates a schematic diagram of a two-level LED security lightin accordance to the third exemplary embodiment of the presentdisclosure.

FIG. 6 illustrates a schematic diagram of a two-level LED security lightin accordance to the fourth exemplary embodiment of the presentdisclosure.

FIG. 7 illustrates a schematic diagram of a two-level LED security lightin accordance to the fifth exemplary embodiment of the presentdisclosure.

FIGS. 8A, 8B, 8C and 8D schematically and respectively show I-Vrelationship charts (Forward Current vs. Forward Voltage) for a whiteLED chip from each of 4 different LED manufacturers.

FIG. 9 is a data sheet showing data of the minimum forward voltages andmaximum forward voltages collected from various LED manufacturers.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is made in detail to the exemplary embodiments of the presentdisclosure, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers are used in thedrawings and the description to refer to the same or alike parts.

First Exemplary Embodiment

Refer to FIG. 1, which schematically illustrates a block diagram of atwo-level LED security light in accordance to the first exemplaryembodiment of the present disclosure. A two-level LED security light(herein as the lighting apparatus)100 includes a power supply unit 110,a light sensing control unit 120, a motion sensing unit 130, a loadingand power control unit 140, and a light-emitting unit 150. The powersupply unit 110 is used for supplying power required to operate thesystem, wherein the associated structure includes the known AC/DCvoltage converter. The light sensing control unit 120 may be aphotoresistor, which may be coupled to the loading and power controlunit 140 for determining daytime or nighttime in accordance to theambient light. The motion sensing unit 130 may be a passive infraredsensor (PIR), which is coupled to the loading and power control unit 140and is used to detect intrusions. When a person is entering apredetermined detection zone of the motion sensing unit 130, a sensingsignal thereof may be transmitted to the loading and power control unit140.

The loading and power control unit 140 which is coupled to thelight-emitting unit 150 may be implemented by a microcontroller. Theloading and power control unit 140 may control the illumination levelsof the light-emitting unit 150 in accordance to the sensing signaloutputted by the light sensing control unit 120 and the motion sensingunit 130. The light-emitting unit 150 may include a plurality of LEDsand switching components. The loading and power control unit 140 maycontrol the light-emitting unit 150 to generate at least two levels ofillumination variations.

When the light sensing control unit 120 detects that the ambient lightis lower than a predetermined value (i.e., nighttime), the loading andpower control unit 140 executes the Photo-Control (PC) mode by turningon the light-emitting unit 150 to generate a high level illumination fora predetermined duration then return to a low level illumination forPower-Saving (PS) mode. When the light sensing control unit 120 detectsthat the ambient light is higher than a predetermined value (i.e.,dawn), the loading and power control unit 140 turns off thelight-emitting unit 150.In the PS mode, when the motion sensing unit 130detects a human motion, the loading and power control unit 140 mayincrease the electric current which flow through the light-emitting unit150, to generate the high level illumination for a short predeterminedduration. After the short predetermined duration, the loading and powercontrol unit 140 may automatically lower the electric current that flowthrough the light-emitting unit 150 thus have the light-emitting unit150 return to low level illumination for saving energy.

Refer to 2A, which illustrates a schematic diagram of a two-level LEDsecurity light in accordance to the first exemplary embodiment of thepresent disclosure. The light sensing control unit 120 may beimplemented by a light sensor 220; the motion sensing unit 130 may beimplemented by a motion sensor 230; the loading and power control unit140 may be implemented by a microcontroller 240. The light-emitting unit250 includes three series-connected LEDs L1˜L3. The LEDs L1˜L3 isconnected between a DC source and a transistor Q1, wherein the DC sourcemay be provided by the power supply unit 110. The transistor Q1 may bean N-channel metal-oxide-semiconductor field-effect-transistor (NMOS).The transistor Q1 is connected between the three series-connected LEDsL1˜L3 and a ground GND. The loading and power control unit 140implemented by the microcontroller 240 may output a pulse widthmodulation (PWM) signal to the gate of transistor Q1 to control theaverage electric current. It is worth to note that the electriccomponents depicted in FIG. 2A only serves as an illustration for theexemplary embodiment of the present disclose and hence the presentdisclosure is not limited thereto.

Refer to FIG. 2B concurrently, which graphically illustrates a timingwaveform of a pulse width modulation (PWM) signal in accordance to thefirst exemplary embodiment of the present disclosure. In the PC mode,the PWM signal may be used to configure the transistor Q1 to have theconduction period T_(off) being longer than the cut-off period T_(off) .On the other hand in the PS mode, the PWM signal may configure thetransistor Q1 to have the conduction period T_(on) being shorter thanthe cut-off period T_(off). In comparison of the illumination levelsbetween the PC and PS modes, as the conduction period T_(on) oftransistor Q1 being longer under the PC mode, therefore have higheraverage electric current driving the light-emitting unit 250 therebygenerate high illumination, which may be classified as the high levelillumination; whereas as the conduction period T_(on) of transistor Q1is shorter in the PS mode, therefore have lower average electric currentdriving the light-emitting unit 250 thereby generate low illumination,which may be classified as the low level illumination.

The microcontroller 240 turns off the light-emitting unit 250 during theday and activates the PC mode at night by turning on the light-emittingunit 250 to generate the high level illumination for a shortpredetermined duration then return to the low level illumination therebyentering the PS mode. When the motion sensor 230 detects a human motionin the PS mode, the light-emitting unit 250 may switch to the high levelillumination for illumination or warning application. The light-emittingunit 250 may return to the low level illumination after maintaining atthe high level illumination for a short predetermined duration to saveenergy.

In addition, the microcontroller 240 is coupled to a time setting unit260, wherein the time setting unit 260 may allow the user to configurethe predetermined duration associated with the high level illuminationin the PC mode, however the present disclosure is not limited thereto.The time setting unit is a type of external control units designed todetect various external control signals and to convert the variousexternal control signals into various message signals interpretable bythe controller for setting various operating parameters of a securitylight including at least a time length setting for various illuminationmodes, a light intensity setting for various illumination modes andswitching between illumination modes. The external control units may beconfigured with a push button, a touch sensor, a voltage divider, apower interruption detection circuitry or a wireless remote controlreceiver for generating message signals interpretable by the controller.

Second Exemplary Embodiment

Refer again to FIG. 1, wherein the illumination variations of thelight-emitting unit 150 may be implemented through the number oflight-source loads being turned on to generate more than two levels ofillumination. The lighting apparatus 100 in the instant exemplaryembodiment may be through turning on a portion of LEDs or all the LEDsto generate a low and a high level of illuminations.

Refer to FIG. 3A concurrently, which illustrates a schematic diagram ofa two-level LED security light 100 in accordance to the second exemplaryembodiment of the present disclosure. The main difference between FIG.3A and FIG. 2A is in the light-emitting unit 350, having threeseries-connected LEDs L1˜L3 and NMOS transistors Q1 and Q2. The LEDsL1˜L3 are series connected to the transistor Q1 at same time connectedbetween the DC source and a constant electric current control circuit310. Moreover, transistor Q2 is parallel connected to the two endsassociated with LEDs L2 and L3. The gates of the transistors Q1 and Q2are connected respectively to a pin PC and a pin PS of themicrocontroller 240. The constant electric current control circuit 310in the instant exemplary embodiment maintains the electric current inthe activated LED at a constant value, namely, the LEDs L1˜L3 areoperated in constant-current mode.

Refer to FIG. 3A, the pin PC of the microcontroller 240 controls theswitching operations of the transistor Q1; when the voltage level of pinPC being either a high voltage or a low voltage, the transistor Q1 mayconduct or cut-off, respectively, to turn the LEDs L1˜L3 on or off. Thepin PS of the microcontroller 240 controls the switch operations of thetransistor Q2, to form two current paths 351 and 352 on thelight-emitting unit 350. When the voltage at the pin PS of themicrocontroller 240is high, the transistor Q2 conducts, thereby formingthe current path 351 passing through the LED L1 and the transistor Q2;when the voltage at the pin PS being low, the transistor Q2 cuts-off,thereby forming the current path 352 passing through all the LEDs L1˜L3.The microcontroller 240 may then control the switching operation of thetransistor Q2 to turn on the desired number of LEDs so as to generate ahigh or a low level illumination.

When light sensor 220 detects that the ambient light is higher than apredetermined value, the microcontroller 240 through the pin PC outputsa low voltage, which causes the transistor Q1 to cut-off and turns offall the LEDs L1˜L3 in the light-emitting unit 350. Conversely, when thelight sensor 220 detects that the ambient light is lower than thepredetermined value, the microcontroller 240 activates the PC mode,i.e., outputting a high voltage from pin PC and a low voltage from pinPS, to activate the transistor Q1 while cut-off the transistor Q2,thereby forming the current path 352, to turn on the three LEDs L1˜L3 inthe light-emitting unit 350 so as to generate the high levelillumination for a predetermined duration. After the predeterminedduration, the microcontroller 240 may switch to the PS mode by havingthe pin PC continue outputting a high voltage and the pin PS outputtinga high voltage, to have the transistor Q2 conducts, thereby forming thecurrent path 351. Consequently, only the LED L1 is turned on and the lowlevel illumination is generated.

When the motion sensor detects a human motion in the PS mode, the pin PSof the microcontroller 240 temporarily switches from the high voltage toa low voltage, to have the transistor Q2 temporarily cuts-off thusforming the current path 352 to activate all the LEDs in thelight-emitting unit 350, thereby temporarily generates the high levelillumination. The light-emitting unit 350 is driven by a constantelectric current, therefore the illumination level generated thereof isdirectly proportional to the number of LEDs activated. FIG. 3Billustrates another implementation for FIG. 3A, wherein the relays J1and J2 are used in place of NMOS transistors to serve as switches. Themicrocontroller 240 may control the relays J2 and J1 through regulatingthe switching operations of the NPN bipolar junction transistors Q4 andQ5. Moreover, resistors R16 and R17 are current-limiting resistors.

In the PC mode, the relay J1 being pull-in while the relay J2 bounce offto have constant electric current driving all the LEDs L1˜L3 to generatethe high level illumination; in PS mode, the relays J1 and J2 bothpull-in to have constant electric current only driving the LED L1 thusthe low level illumination may be thereby generated. Furthermore, whenthe motion sensor 230 detects a human motion, the pin PS of themicrocontroller 240 may temporarily switch from high voltage to lowvoltage, forcing the relay J2 to temporarily bounce off and the relay J1pull-in so as to temporarily generate the high level illumination.

The LED L1 may adopt a LED having color temperature of 2700K while theLEDs L2 and L3 may adopt LEDs having color temperature of 5000K in orderto increase the contrast between the high level and the low levelilluminations. The number of LEDs included in the light-emitting unit350 may be more than three, for example five or six LEDs. The transistorQ2 may be relatively parallel to the two ends associated with aplurality of LEDs to adjust the illumination difference between the highand the low illumination levels. Additionally, the light-emitting unit350 may include a plurality of transistors Q2, which are respectivelycoupled to the two ends associated with each LED to provide morelighting variation selections. The microcontroller 240 may decide thenumber of LEDs to turn on in accordance to design needs at differentconditions. Based on the explanation of the aforementioned exemplaryembodiment, those skills in the art should be able to deduce otherimplementation and further descriptions are therefore omitted.

Third Exemplary Embodiment

Refer back to FIG. 1, wherein the light-emitting unit 150 may include aphase controller and one or more parallel-connected alternating current(AC) LEDs. The phase controller is coupled between the described one ormore parallel-connected ACLEDs and AC power source. The loading andpower controller 140 in the instant exemplary embodiment may through thephase controller adjust the average power of the light-emitting unit 150so as to generate variations in the low level and the high levelilluminations.

Refer to FIG. 4A, which illustrates a schematic diagram of a two-levelLED security light 100 in accordance to the third exemplary embodimentof the present disclosure. The main difference between FIG. 4A and FIG.3 is in that the light-source load is an ACLED, which is coupled to theAC power source, and further the light-emitting unit 450 includes aphase controller 451. The phase controller 451 includes a bi-directionalswitching device 452, here, a triac, a zero-crossing detection circuit453, and a resistor R. The microcontroller 240 turns off thelight-emitting unit 450 when the light sensor 220 detects that theambient light is higher than a predetermined value. Conversely, when thelight sensor 220 detects that the ambient light is lower than thepredetermined value, the microcontroller 240 activates the PC mode byturning on the light-emitting unit 450. In the PC mode, themicrocontroller 240 may select a control pin for outputting a pulsesignal which through a resistor R triggers the triac 452 to have a largeconduction angle. The large conduction angle configures thelight-emitting unit 450 to generate a high level illumination for apredetermined duration. Then the microcontroller 240 outputs the pulsesignal for PS mode through the same control pin to trigger thetriac 452to have a small conduction angle for switching the light-emitting unit450 from the high level illumination to the low level illumination ofthe PS mode. Moreover, when the motion sensor 230 (also called motionsensing unit) detects a human motion in the PS mode, the microcontroller240 temporarily outputs the PC-mode pulse signal through the samecontrol pin to have the light-emitting unit 450 generated the high levelillumination for a short predetermined duration. After the shortpredetermined duration, the light-emitting unit 450 returns to the lowlevel illumination.

In the illumination control of the ACLED, the microcontroller 240 mayutilize the detected zero-crossing time (e.g., the zero-crossing time ofan AC voltage waveform) outputted from the zero-crossing detectioncircuit 453 to send an AC synchronized pulse signal thereof which maytrigger the triac 452 of the phase controller 451 thereby to change theaverage power input to the light-emitting unit 450. As the ACLED has acut-in voltage V_(t) for start conducting, thus if the pulse signalinaccurately in time triggers the conduction of the triac 452, then theinstantaneous value of AC voltage may be lower than the cut-in voltageV_(t) of ACLED at the trigger pulse. Consequently, the ACLED may resultin the phenomenon of either flashing or not turning on. Therefore, thepulse signal generated by the microcontroller 240 must fall in a propertime gap behind the zero-crossing point associated with the ACsinusoidal voltage waveform.

Supposing an AC power source having a voltage amplitude V_(m) andfrequency f, then the zero-crossing time gap t_(D) of the trigger pulseoutputted by the microcontroller 240 should be limited according tot_(o)<t_(D)<1/2f−t_(o) for a light-source load with a cut-in voltageV_(t), wherein t_(o)=(1/2;πf)sin⁻¹(V_(t)/V_(m)). The described criterionis applicable to all types of ACLEDs to assure that the triac 452 can bestably triggered in both positive and negative half cycle of the ACpower source. Take ACLED with V_(t)(rms)=80V as an example, andsupposing the V_(m)(rms)=110V and f=60 Hz, then t_(o)=2.2 ms and(1/2f)=8.3 ms may be obtained. Consequently, the proper zero-crossingtime gap t_(D) associated with the phase modulation pulse outputted bythe microcontroller 240 which lagged the AC sinusoidal voltage waveformshould be designed in the range of 2.2 ms<t_(D)<6.1 ms.

Refer to FIG. 4B, which illustrates a timing waveform of the two-levelLED security light in accordance to the third exemplary embodiment ofthe present disclosure. Waveforms (a)˜(d) of FIG. 4B respectivelyrepresent the AC power source, the output of the zero-crossing detectioncircuit 453, the zero-crossing delay pulse at the control pin of themicrocontroller 240, and the voltage waveform across the two ends of theACLED in the light-emitting unit 450. The zero-crossing detectioncircuit 453 converts the AC voltage sinusoidal waveform associated withthe AC power source to a symmetric square waveform having a low and ahigh voltage levels as shown in FIG. 4B(b). At the zero-crossing pointof the AC voltage sinusoidal wave, the symmetric square waveform maytransit either from the low voltage level to the high voltage level orfrom the high voltage level to the low voltage level. Or equivalently,the edge of the symmetric square waveform in the time domain correspondsto the zero-crossing point of the AC voltage sinusoidal waveform. Asshown in FIG. 4B(c), the microcontroller 240 outputs a zero-crossingdelay pulse in correspondence to the zero-crossing point of the ACsinusoidal waveform in accordance to the output waveform of thezero-crossing detection circuit 453. The zero-crossing delay pulse isrelative to an edge of symmetric square waveform behind a time gap t_(D)in the time domain. The t_(D) should fall in a valid range, as describedpreviously, to assure that the triac 452 can be stably triggered therebyto turn on the ACLED. FIG. 4B(d) illustrates a voltage waveform appliedacross the two ends associated with the ACLED. The illumination level ofthe light-emitting unit 450 is related to the conduction period t_(on)of the ACLED, or equivalently, the length t_(on) is directlyproportional to the average power inputted to the ACLED. The differencebetween the PC mode and the PS mode being that in the PC mode, the ACLEDhas longer conduction period, thereby generates the high levelillumination; whereas in the PS mode, the ACLED conduction period isshorter, hence generates the low level illumination.

Refer to FIG. 5, which illustrates a schematic diagram of a two-levelLED security light 100 in accordance to the third exemplary embodimentof the present disclosure. The light-emitting unit 550 of the lightingapparatus 100 includes an ACLED1, an ACLED2, and a phase controller 551.The phase controller 551 includes triacs 552 and 553, the zero-crossingdetection circuit 554 as well as resistors R1 and R2. The light-emittingunit 550 of FIG. 5 is different from the light-emitting unit 450 of FIG.4 in that the light-emitting unit 550 has more than one ACLEDs and morethan one bi-directional switching devices. Furthermore, the colortemperatures of the ACLED1 and the ACLED2 may be selected to bedifferent.

In the exemplary embodiment of FIG. 5, the ACLED1 has a high colortemperature, and the ACLED2 has a low color temperature. In the PC mode,the microcontroller 240 uses the phase controller 551 to trigger bothACLED1 and ACLED2 to conduct for a long period, thereby to generate thehigh level illumination as well as illumination of mix colortemperature. In the PS mode, the microcontroller 240 uses the phasecontroller 551 to trigger only the ACLED2 to conduct for a short period,thereby generates the low level illumination as well as illumination oflow color temperature. Moreover, in the PS mode, when the motion sensor230 detects a human motion, the microcontroller 240 may through thephase controller 551 trigger the ACLED1 and ACLED2 to conduct for a longperiod. Thereby, it may render the light-emitting unit 450 to generatethe high level illumination of high color temperature and to producehigh contrast in illumination and hue, for a short predeterminedduration to warn the intruder. Consequently, the lighting apparatus maygenerate the high level or the low level illumination of different hue.The rest of operation theories associated with the light-emitting unit550 are essentially the same as the light-emitting unit 450 and furtherdescriptions are therefore omitted.

Fourth Exemplary Embodiment

Refer to FIG. 6, which illustrates a schematic diagram of a two-levelLED security light 100 in accordance to the fourth exemplary embodimentof the present disclosure. The light-emitting unit 150 of FIG. 1 may beimplemented by the light-emitting unit 650, wherein the light-emittingunit 650 includes three ACLED1˜3 having identical luminous power as wellas switches 651 and 652. In which, switches 651 and 652 may be relays.The parallel-connected ACLED1 and ACLED2 are series-connected to theswitch 652 to produce double luminous power, and of which the ACLED3 isparallel connected to, to generate triple luminous power, and of whichan AC power source is further coupled to through the switch 651.Moreover, the microcontroller 240 implements the loading and powercontrol unit 140 of FIG. 1. The pin PC and pin PS are respectivelyconnected to switches 651 and 652 for outputting voltage signals tocontrol the operations of switches 651 and 652 (i.e., open or close).

In the PC mode, the pin PC and pin PS of the microcontroller 240 controlthe switches 651 and 652 to be closed at same time. Consequently, theACLED1˜3 are coupled to the AC power source and the light-emitting unit650 may generate a high level illumination of triple luminous power.After a short predetermined duration, the microcontroller 240 returns toPS mode. In which the switch 651 is closed while the pin PS controls theswitch 652 to be opened, consequently, only the ACLED3 is connected toAC power source, and the light-emitting unit 650 may thus generate thelow level illumination of one luminous power. In the PS mode, when themotion sensor 230 detects a human motion, the microcontroller 240temporarily closes the switch 652 to generate high level illuminationwith triple luminous power for a predetermined duration. After thepredetermined duration, the switch 652 returns to open status thereby togenerate the low level illumination of one luminous power. The lightingapparatus of FIG. 6 may therefore through controlling switches 651 and652 generate two level illuminations with illumination contrast of atleast 3 to 1.

The ACLED1 and ACLED2 of FIG. 6 may be high power lighting sourceshaving color temperature of 5000K. The ACLED3 may be a low powerlighting source having color temperature of 2700K. Consequently, theACLED may generate two levels of illuminations with high illuminationand hue contrast without using a zero-crossing detection circuit.

Fifth Exemplary Embodiment

Refer to FIG. 7, which illustrates a schematic diagram of a two-levelLED security light in accordance to the fifth exemplary embodiment ofthe present disclosure. The light-emitting unit 750 of FIG. 7 isdifferent from the light-emitting unit 640 of FIG. 6 in that the ACLED3is series-connected to a circuit with a rectified diode D and a switch753 parallel-connected together, and of which is further coupled througha switch 751 to AC power source. When the switch 753 closes, the ACelectric current that passes through the ACLED3 may be a full sinusoidalwaveform. When the switch 753 opens, the rectified diode rectifies theAC power, thus only one half cycle of the AC electric current may passthrough the ACLED, consequently the luminous power of ALCED3 is cut tobe half.

The pin PS of the microcontroller 240 synchronously controls theoperations of switches 752 and 753.If the three ACLED1˜3 have identicalluminous power, then in the PC mode, the pin PC and pin PS of themicrocontroller 240 synchronously close the switches 751˜753 to renderACLED1˜3illuminating, thus the light-emitting unit 750 generates a highlevel illumination which is three-times higher than the luminous powerof a single ACLED. When in the PS mode, the microcontroller 240 closesthe switch 751 while opens switches 752 and 753. At this moment, onlythe ACLED3 illuminates and as the AC power source is rectified by therectified diode D, thus the luminous power of ACLED3 is half of the ACpower source prior to the rectification. The luminous power ratiobetween the high level and the low level illuminations is therefore 6to 1. Consequently, strong illumination contrast may be generated toeffectively warn the intruder.

It should be noted that the light-emitting unit in the fifth exemplaryembodiment is not limited to utilizing ACLEDs. In other words, thelight-emitting unit may include any AC lighting sources such as ACLEDs,incandescent lamps, or fluorescent lamps.

A lighting apparatus may be implemented by integrating a plurality ofLEDs with a microcontroller and various types of sensor components inthe controlling circuit in accordance to the above described fiveexemplary embodiments. This lighting apparatus may automaticallygenerate high level illumination when the ambient light detected isinsufficient and time-switch to the low level illumination. In addition,when a person is entering the predetermined detection zone, the lightingapparatus may switch from the low level illumination to the high levelillumination, to provide the person with sufficient illumination or togenerate strong illumination and hue contrast for monitoring theintruder.

When the light source of the light emitting unit 150 is confined to theuse of an LED load, the compliance and satisfaction of a voltageoperating constraint attributable to the unique electricalcharacteristics of the LED load is vital to a successful performance ofan LED lighting device. Any LED lighting device failing to comply withthe voltage operating constraint of the unique electricalcharacteristics is bound to become a trouble art. This is because theLED as a kind of solid state light source has completely differentelectrical characteristics for performing light emission compared withconventional light source such as incandescent bulbs or fluorescentbulbs. For instance, for a white light or blue light LED there exists avery narrow voltage domain ranging from a threshold voltage at 2.5 voltsto a maximum working voltage at 3.3 volts, which allows to operateadequately and safely the LED; in other words, when a forward voltageimposed on the LED is lower than the threshold voltage, the LED is notconducted and therefore no light is emitted, when the forward voltageexceeds the maximum working voltage, the heat generated by a forwardcurrent could start damaging the construction of the LED. Therefore, theforward voltage imposed on the LED is required to operate between thethreshold voltage and the maximum working voltage.

In respect to the LED load of the light-emitting unit 150, the cut-involtage V_(t) of ACLEDs is technically also referred to as the thresholdvoltage attributable to PN junctions manufactured in LEDs. Morespecifically, the LED is made with a PN junction semiconductor structureinherently featured with three unique electrical characteristics, thefirst characteristic is one-way electric conduction through the PNjunction fabricated in the LED, the second electrical characteristic isthe threshold voltage V_(th) required to trigger the LED to startemitting light and the third electrical characteristic is a maximumworking voltage V_(max) allowed to impose on the LED to avoid a thermalrunaway to damage or burn out the semiconductor construction of the LED.The described cut-in voltage V_(t) has the same meaning as the abovementioned threshold voltage V_(th) which is a more general term to beused for describing the second electrical characteristic of a PNjunction semiconductor structure. Also because the cut-in voltage V_(t)is specifically tied to forming a formula to transform the thresholdvoltage into a corresponding time phase of AC power for lightingcontrol, it is necessary to use the term V_(th) as a neutral word fordescribing the LED electrical characteristics to avoid being confusedwith the specific application for ACLED alone. Additionally, it is to beclarified that the term V_(m) is related to the amplitude of the instantmaximum voltage of an AC power source which has nothing to do with thethird electrical characteristic V_(max) of an LED load.

An LED chip is a small piece of semiconductor material with at least oneLED manufactured inside the semiconductor material. A plurality of LEDsmay be manufactured and packaged inside an LED chip for different levelsof wattage specification to meet different illumination need. For eachLED chip designed with a different level of wattage specification therealways exists a narrow voltage domain V_(th)<V<V_(max), wherein V is avoltage across the LED chip, V_(th) is the threshold voltage to enablethe LED chip to start emitting light and V_(max) is the maximum workingvoltage allowed to impose on the LED chip to protect the LED chip frombeing damaged or burned out by the heat generated by a higher workingvoltage exceeding V_(max).

For an LED load configured with a plurality of the LED chips in any LEDlighting device, regardless such LED load being configured with ACLEDchips or DC LED chips, the working voltage V of each single LED chip isrequired to operate in a domain between a threshold voltage V_(th) and amaximum working voltage V_(max) or V_(th)<V<V_(max) and the workingvoltage V_(N) of the LED load comprising N pieces of LED chips connectedin series is therefore required to operate in a domain established by athreshold voltage of N times V_(th)N×V_(th)) and a maximum workingvoltage of N times V_(max)(N×V_(max)) or N×V_(th)<V_(N)<N×V_(max),wherein N is the number of the LED chips electrically connected inseries. For any LED lighting device comprising an LED load it isrequired that the LED load in conjunction with an adequate level ofpower source is configured with a combination of in series and inparallel connections of LED chips such that the electric current passingthrough each LED chip of the LED load remains at an adequate level suchthat a voltage V across each LED chip complies with an operatingconstraint of V_(th)<V<V_(max) featuring electrical characteristics ofthe LED chip or a voltage V_(N) across the LED load configured with Nnumber of LED chips connected in series complies with an operatingconstraint of N×V_(th)<V_(N)<N×V_(max). Such narrow operating rangetherefore posts an engineering challenge for a circuit designer tosuccessfully design an adequate level of power source and a reliablecircuitry configured with an adequate combination of in seriesconnection and in parallel connection of LED chips for operating ahigher power LED security light.

FIGS. 8A, 8B, 8C and 8D comprises 4 drawings schematically andrespectively showing a I-V relationship chart (Forward Current vs.Forward Voltage) for a white light LED chip from each of 4 different LEDmanufacturers; as can be seen from the chart when a forward voltage V isbelow a minimum forward voltage at around 2.5 volts, the LED chip is notconducted so the current I is zero, as the forward voltage exceeds 2.5volts the LED chip is activated to generate a current flow to emitlight, as the forward voltage continues to increase, the current Iincreases exponentially at a much faster pace, at a maximum forwardvoltage around 3.3 volts the current I becomes 250 mA which generates aheat that could start damaging the PN junction of the LED chip. Theminimum forward voltage, i.e., the threshold voltage or the cut-involtage, and the maximum forward voltage are readily available in thespecification sheets at each of LED manufacturers, such as Cree,Lumileds, Samsung, Osram, and etc. Different LED manufacturers may haveslightly different figures due to manufacturing process but thedeviations of differences are negligible. The constraints of minimumforward voltage and maximum forward voltage represent physicalproperties inherent in any solid state light source. They are necessarymatter for configuring any LED lighting products to ensure a normalperformance of an LED load.

FIG. 9 is a data sheet showing data of the minimum forward voltages andmaximum forward voltages collected from various LED manufacturers. Theyare fundamental requirements for configuring any LED lighting controldevices to ensure a successful performance of any LED lighting device.

In summary, the compliance of voltage operating constraintV_(th)<V<V_(max) featuring electrical characteristics of an LED chip isa critical technology for ensuring a normal performance of the LED load.Failing to comply with such voltage operating constraint can quickly ageor seriously damage the semiconductor structure of the LED chip with aconsequence of quick lumens depreciation of the LED bulbs and theproduct lifetime being substantially shortened, which will beunacceptable to the consumers. The compliance of the operatingconstraint V_(th)<V<V_(max) is a necessary matter for any LED lightingdevice though it is not an obvious matter as it requires complicatedtechnologies to calculate and coordinate among an adequate level ofpower source, a control circuitry and a non-linear light emitting load.For conventional lighting load such as incandescent bulb there exists nosuch operating constraint. This is why in the past years there had beenmany consumers complaining about malfunction of LED bulbs that theconsumers were frustrated with the fast depreciation of lumens outputand substantially shortened product lifetime of the LED bulbs purchasedand used. A good example was a law suit case filed by the Federal TradeCommission on Sep. 7, 2010 (Case No. SACV10-01333 JVS) for a complaintagainst a leading lighting manufacturer for marketing deceptive LEDlamps and making false claims with respect to the life time of their LEDlamps and a huge amount of monetary relief was claimed with the Court inthe complaint.

The present disclosure of a two-level LED security light provides aunique life-style lighting solution. The motivation of creating suchlife-style lighting solution has less to do with the energy savingaspect of the low level illumination mode because an LED is already avery energy saving light source compared with the conventionalincandescent light source. For instance, a 10-watt LED security lightwhen operated at a low level at 30% illumination it only saves 7 watts,which is not as significant as a 100-watt incandescent bulb which cansave as much as 70 watts when operated at 30% illumination for a lowlevel mode. While it is always good to save some extra energy, it ishowever not the main incentives for developing the present invention;the life-style lighting solution of the present disclosure is featuredwith two innovations which meaningfully improve the exquisite tastes ofliving in the evening, the first innovation is the creation of anaesthetic scene for the outdoor living environment, wherein at dusk theLED security light is automatically turned on by the photo sensor toperform the low level illumination with a low color temperature which isnecessary for creating a soft and aesthetic night scene for the outdoorliving area (such soft and aesthetic night view is not achievable by thehigh level illumination however), the second innovation is the creationof a navigation capacity similar to a light house effect for guidingpeople to safely move toward a destination in the outdoor living areawithout getting lost or encountering an accident, wherein when a motionintrusion is detected by the motion sensor the security light isinstantly changed to perform a high level illumination mode with a highcolor temperature light which offers people a high visibility of thesurrounding environment when needed. For the visibility of a surroundingenvironment the high color temperature light is the winner while for thecreation of a soft and aesthetic night view there is no substitute forthe low color temperature light. It is the innovation of the presentinvention to configure a life-style security light with a low colortemperature LED load and a high color temperature LED load respectivelyactivated by a photo sensor and a motion sensor to resemble the naturalphenomenon of a sun light. These two innovative functions ideallyimplemented by the LED loads coupled with the motion sensor to increaseillumination with a high visibility when people enters into the shortdetection area make the present invention a perfect life-style lightingsolution for enjoying an exquisite taste of evening life.

The above-mentioned descriptions represent merely the exemplaryembodiment of the present disclosure, without any intention to limit thescope of the present disclosure thereto. Various equivalent changes,alternations or modifications based on the claims of present disclosureare all consequently viewed as being embraced by the scope of thepresent disclosure.

What is claimed is:
 1. An LED security light comprising: alight-emitting unit comprising a plurality of LEDs divided into two LEDloads connected in parallel, including a first LED load with N numberLEDs emitting light with a low light color temperature and a second LEDload with M number LEDs emitting light with a high light colortemperature, wherein M and N are positive integers; a light diffusercovering the first LED load and the second LED load to create a diffusedlight with a diffused light color temperature; a loading and powercontrol unit; a light sensing control unit; a power supply unit; and anexternal control unit including at least a first external control deviceoutputting at least one first external control signal to activate adiffused light color temperature tuning process and to select thediffused light color temperature; wherein the loading and power controlunit comprises a controller and a switching circuitry, wherein theswitching circuitry is electrically coupled between at least one DCpower source of the power supply unit and the light-emitting unit,wherein the switching circuitry comprises a first semiconductorswitching device electrically connected to the first LED load and asecond semiconductor switching device electrically connected to thesecond LED load; wherein the controller is electrically coupled with thefirst semiconductor switching device, the second semiconductor switchingdevice, the light sensing control unit and at least the first externalcontrol device; wherein when the light-emitting unit is in a turned onstate, the controller further outputs a first control signal to controla first conduction rate of the first semiconductor switching device anda second control signal to control a second conduction rate of thesecond semiconductor switching device to respectively deliver a firstelectric power to the first LED load and a second electric power to thesecond LED load to generate the diffused light with the diffused lightcolor temperature thru the diffuser according to the at least one firstexternal control signal; wherein for tuning the diffused light colortemperature to a lower diffused light color temperature, the controllerupon receiving the at least one first external control signal operatesto increase the first conduction rate of the first semiconductorswitching device to increase the first electric power delivered to thefirst LED load and simultaneously operates to decrease the secondconduction rate of the second semiconductor switching device to decreasethe second electric power delivered to the second LED load with the samepace such that a total diffused light intensity remains essentiallyunchanged while the diffused light color temperature is accordinglyadjusted to the lower diffused light color temperature; wherein fortuning the diffused light color temperature to a higher diffused lightcolor temperature, the controller upon receiving the at least one firstexternal control signal operates to decrease the first conduction rateof the first semiconductor switching device to decrease the firstelectric power delivered to the first LED load and simultaneouslyoperates to increase the second conduction rate of the secondsemiconductor switching device to increase the second electric powerdelivered to the second LED load with the same pace such that the totallight intensity generated by the light emitting unit remains essentiallyunchanged while the diffused light color temperature is accordinglyadjusted to the higher diffused light color temperature; wherein when anambient light detected by the light sensing control unit is lower than afirst predetermined value, the loading and power control unit operatesto turn on the light-emitting unit to perform the diffused light with aselected diffused light color temperature; wherein when the ambientlight detected by the light sensing control unit is higher than a secondpredetermined value, the loading and power control unit manages to turnoff all the LEDs in the light-emitting unit; wherein the N number LEDsof the first LED load and the M number LEDs of the second LED load arerespectively designed with a configuration of in series and/or inparallel connections such that when incorporated with a power levelsetting of the at least one DC power source an electric current passingthrough each LED of the first LED load and each LED of the second LEDload remains at an adequate level such that a voltage V across each LEDcomplies with an operating constraint of V_(th)<V<V_(max) featuringelectrical characteristics of a LED, where V_(th) is a threshold voltagerequired to trigger the LED to start emitting light and V_(max) is amaximum operating voltage across the LED to avoid a thermal damage orburning out of LED construction.
 2. The LED security light according toclaim 1, wherein when each of the first LED load and the second LED loadis configured with a plurality of LEDs, or sets of in parallel connectedLEDs, electrically connected in series, a working voltage across each ofthe first LED load and the second LED load is confined in a domainbetween a minimum voltage equal to the sum of the threshold voltages ofall LEDs electrically connected in series or sets of in parallelconnected LEDs electrically connected in series and a maximum voltageequal to the sum of the maximum operating voltages of all LEDselectrically connected in series or sets of in parallel connected LEDselectrically connected in series.
 3. The LED security light according toclaim 2, wherein when the LED has the voltage V across each LEDcomplying with an operating constraint of 2.5volts <V_(th)<V<V_(max)<3.5volts and the first LED load and the second LED load are required tooperate with respective operating voltages V_(N) and V_(M) confined indomains expressed by N_(S)×2.5 volts<V_(N)<N_(S)×3.5 volts and M_(S)×2.5volts<V_(M)<M_(S)×3.5 volts, with N_(S) and M_(S) respectively denotingthe numbers of series connected LEDs in the first LED load and thesecond LED load, wherein N_(S)≤N and M_(S)≤M.
 4. The LED security lightaccording to claim 1, wherein the controller is designed with a diffusedlight color temperature switching scheme comprising a plurality ofdifferent diffused light color temperature performances to berespectively activated by different first external control signalsgenerated by the first external control device, wherein different pairedcombinations of the first conduction rate and the second conduction raterespectively for controlling the first electric power delivered to thefirst LED load and the second electric power delivered to the second LEDload for creating different diffused light color temperatureperformances are preprogrammed and stored in a memory unit addressableby the controller for operating a pick and play process according to theat least one first external control signal generated by the firstexternal control device for selecting a corresponding diffused lightcolor temperature performance in the diffused light color temperatureswitching scheme.
 5. The LED security light according to claim 1,wherein M is equal to N.
 6. The LED security light according to claim 1,wherein M is smaller than N.
 7. The LED security light according toclaim 4, wherein the at least one first external control signal is ashort power interruption signal generated by a main power switch, a pushbutton, a touch sensor or a wireless remote control device wherein apower interruption detection circuit is electrically coupled with thecontroller, wherein when the short power interruption signal is detectedby the power interruption detection circuit and converted into a messagesensing signal interpretable by the controller, the controller operatesto alternately perform the corresponding diffused light colortemperature performance in the diffused light color temperatureswitching scheme according to a prearranged sequence.
 8. The LEDsecurity light according to claim 7, wherein when the main power switchis used for generating the short power interruption signal, the mainpower switch is turned off and turned back on within a predeterminedtime interval.
 9. The LED security light according to claim 7, whereinwhen the push button or the touch sensor is used for generating theshort power interruption signal, a signal detection circuitry isconnected to the push button switch or the touch sensor, wherein whenthe push button switch or the touch sensor is operated for a short timeinterval a voltage signal with a time length equal to the short timeinterval is transmitted to the signal detection circuitry and the signaldetection circuitry accordingly manages to transmit the short powerinterruption signal to the power interruption detection circuit forconverting to the message sensing signal interpretable by thecontroller, the controller accordingly operates to alternately performthe corresponding diffused light color temperature performance in thediffused light color temperature switching scheme according to aprearranged sequence.
 10. The LED security light according to claim 4,wherein the first external control device is a voltage divider operatedby a user to output a plurality of voltage signals interpretable by thecontroller for executing the pick and play process for selecting andperforming the corresponding diffused light color temperatureperformance in the diffused light color temperature switching scheme.11. The LED security light according to claim 4, wherein the firstexternal control device is a wireless remote control device comprisingat least one wireless external signal receiver electrically coupled withthe controller to receive at least one wireless external control signal,wherein the at least one first external control signal is the at leastone wireless external control interpretable by the controller foractivating the pick and play process to select and perform thecorresponding diffused light color temperature performance in thediffused light color temperature switching scheme.
 12. The LED securitylight according to claim 10, wherein the voltage divider is operatedwith a configuration of a slide switch, a rotary switch, or a pull chainswitch, designed with a plurality of switching positions operable by auser for selecting and performing the corresponding diffused light colortemperature performance from the diffused light color temperatureswitching scheme.
 13. The LED security light according to claim 4,wherein the at least one first external control signal is an infraredlight reflected from an object entering and staying in a detection zone,wherein the first external control device is an active infrared raysensor for detecting the infrared light reflected from the object andconverting the infrared light reflected from the object into the atleast one message sensing signal with a signal format interpretable bythe controller for executing the pick and play process for selecting andperforming the corresponding diffused light color temperatureperformance from the diffused light color temperature switching scheme.14. The LED security light according to claim 4, wherein the diffusedlight color temperature switching scheme comprises at least a highdiffused light color temperature performance and a low diffused lightcolor temperature performance, wherein for performing the high diffusedlight color temperature performance the second semiconductor switchingdevice is fully conducted and the first semiconductor switching deviceis completely cut off, wherein for performing the low diffused lightcolor temperature performance the first semiconductor switching deviceis fully conducted and the second semiconductor switching device iscompletely cut off.
 15. The LED security light according to claim 4,wherein the light color temperature switching scheme comprises at leasta high diffused light color temperature performance, a low diffusedlight color temperature performance and a medium diffused light colortemperature performance, wherein for performing the high diffused lightcolor temperature performance the second semiconductor switching deviceis fully conducted and the first semiconductor switching device iscompletely cut off, wherein for performing the low diffused light colortemperature performance the first semiconductor switching device isfully conducted while the second semiconductor switching device iscompletely cut off, wherein for performing the medium diffused lightcolor temperature performance the first semiconductor switching deviceand the second semiconductor switching device are both partially andcomplementarily conducted such that the total light intensity generatedby the light-emitting unit remains essentially unchanged.
 16. The LEDsecurity light according to claim 1, wherein the low color temperatureis designed in a range between 2200 Kelvins and 3000 Kelvins, the highcolor temperature is designed in the range between 4500 Kelvins and 5000Kelvins.
 17. An LED security light comprising: a light-emitting unitcomprising a plurality of LEDs divided into two LED loads connected inparallel, including a first LED load emitting light with a low lightcolor temperature and a second LED load emitting light with a high lightcolor temperature, wherein M and N are positive integers; a lightdiffuser covering the first LED load and the second LED load to create adiffused light with a diffused light color temperature; a loading andpower control unit; a light sensing control unit; a motion sensing unit;a power supply unit; and an external control unit including at least afirst external control device outputting at least one first externalcontrol signal to activate a diffused light color temperature tuningprocess and to select the diffused light color temperature; wherein theloading and power control unit comprises a controller and a switchingcircuitry, wherein the switching circuitry is electrically coupledbetween at least one DC power source of the power supply unit and thelight-emitting unit, wherein the switching circuitry comprises a firstsemiconductor switching device electrically connected to the first LEDload and a second semiconductor switching device electrically connectedto the second LED load; wherein the controller is electrically coupledwith the first semiconductor switching device, the second semiconductorswitching device, the light sensing control unit, the motion sensingunit and at least the first external control device; wherein when thelight-emitting unit is in a turned on state, the controller furtheroutputs a first control signal to control a first conduction rate of thefirst semiconductor switching device and a second control signal tocontrol a second conduction rate of the second semiconductor switchingdevice to respectively deliver a first electric power to the first LEDload and a second electric power to the second LED load to generate thediffused light with the diffused light color temperature thru thediffuser according to the at least one first external control signal;wherein for tuning the diffused light color temperature to a lowerdiffused light color temperature, the controller upon receiving the atleast one first external control signal operates to increase the firstconduction rate of the first semiconductor switching device to increasethe first electric power delivered to the first LED load andsimultaneously operates to decrease the second conduction rate of thesecond semiconductor switching device to decrease the second electricpower delivered to the second LED load with the same pace such that atotal diffused light intensity remains essentially unchanged while thediffused light color temperature is accordingly adjusted to the lowerdiffused light color temperature; wherein for tuning the diffused lightcolor temperature to a higher diffused light color temperature, thecontroller upon receiving the at least one first external control signaloperates to decrease the first conduction rate of the firstsemiconductor switching device to decrease the first electric powerdelivered to the first LED load and simultaneously operates to increasethe second conduction rate of the second semiconductor switching deviceto increase the second electric power delivered to the second LED loadwith the same pace such that the total light intensity generated by thelight emitting unit remains essentially unchanged while the diffusedlight color temperature is accordingly adjusted to the higher diffusedlight color temperature; wherein when an ambient light detected by thelight sensing control unit is lower than a first predetermined value,the loading and power control unit operates to activate the motionsensing unit; wherein when a motion intrusion is detected by the motionsensing unit, the loading and power control unit operates to deliver anelectric power to the light-emitting unit to generate a high levelillumination with a selected diffused light color temperature accordingto a sensing signal received from the motion sensing unit for apredetermined time duration before resuming to a turned off state of thelight-emitting unit; wherein when the ambient light detected by thelight sensing control unit is higher than a second predetermined value,the loading and power control unit manages to deactivate the motionsensing unit and turn off all LEDs of the light-emitting unit; whereinthe N number LEDs of the first LED load and the M number LEDs of thesecond LED load are respectively designed with a configuration of inseries and/or in parallel connections such that when incorporated with apower level setting of the at least one DC power source an electriccurrent passing through each LED of the first LED load and each LED ofthe second LED load remains at an adequate level such that a voltage Vacross each LED complies with an operating constraint ofV_(th)<V<V_(max) featuring electrical characteristics of a LED, whereV_(th) is a threshold voltage required to trigger the LED to startemitting light and V_(max) is a maximum operating voltage across the LEDto avoid a thermal damage or burning out of LED construction.
 18. TheLED security light according to claim 17, wherein when each of the firstLED load and the second LED load is configured with a plurality of LEDs,or sets of in parallel connected LEDs, electrically connected in series,a working voltage across each of the first LED load and the second LEDload is confined in a domain between a minimum voltage equal to the sumof the threshold voltages of all LEDs electrically connected in seriesor sets of in parallel connected LEDs electrically connected in seriesand a maximum operating voltage equal to the sum of the maximumoperating voltages of all LEDs electrically connected in series or setsof in parallel connected LEDs electrically connected in series.
 19. TheLED security light according to claim 18, wherein when the LED has thevoltage V across each LED complying with an operating constraint of2.5volts<V_(th)<V<V_(max)<3.5 volts and the first LED load and thesecond LED load are required to operate with respective operatingvoltages V_(N) and V_(M) confined in domains expressed by N_(S)×2.5volts<V_(N)<N_(S)×3.5 volts and M_(S)×2.5 volts<V_(M)<M_(S)×3.5 volts,with N_(S) and M_(S) respectively denoting the numbers of seriesconnected LEDs in the the first LED load and the second LED load,wherein N_(S)≤N and M_(S)≤M.
 20. The LED security light according toclaim 17, wherein the controller is designed with a diffused light colortemperature switching scheme comprising a plurality of differentdiffused light color temperature performances to be respectivelyactivated by different first external control signals generated by thefirst external control device, wherein different paired combinations ofthe first conduction rate and the second conduction rate respectivelyfor controlling the first electric power delivered to the first LED loadand the second electric power delivered to the second LED load forcreating different diffused light color temperatures are preprogrammedand stored in a memory unit addressable by the controller for operatinga pick and play process according to the at least one first externalcontrol signal generated by the first external control device forselecting a corresponding diffused light color temperature performancein the diffused light color temperature switching scheme.
 21. The LEDsecurity light according to claim 17, wherein M is equal to N.
 22. TheLED security light according to claim 17, wherein M is smaller than N.23. The LED security light according to claim 20, wherein the at leastone first external control signal is a short power interruption signalgenerated by a main power switch, a push button, a touch sensor or awireless remote control device wherein a power interruption detectioncircuit is electrically coupled with the controller, wherein when theshort power interruption signal is detected by the power interruptiondetection circuit and converted into a message sensing signalinterpretable by the controller, the controller operates to alternatelyperform the corresponding diffused light color temperature performancein the diffused light color temperature switching scheme according to aprearranged sequence.
 24. The LED security light according to claim 23,wherein when the main power switch is used for generating the shortpower interruption signal, the main power switch is turned off andturned back on within a predetermined time interval.
 25. The LEDsecurity light according to claim 23, wherein when the push button orthe touch sensor is used for generating the short power interruptionsignal, a signal detection circuitry is connected to the push buttonswitch or the touch sensor, wherein when the push button switch or thetouch sensor is operated for a short time interval a voltage signal witha time length equal to the short time interval is transmitted to thesignal detection circuitry and the signal detection circuitryaccordingly manages to transmit the short power interruption signal tothe power interruption detection circuit for converting to the messagesensing signal interpretable by the controller, the controlleraccordingly operates to alternately perform the corresponding diffusedlight color temperature performance in the diffused light colortemperature switching scheme according to a prearranged sequence. 26.The LED security light according to claim 20, wherein the first externalcontrol device is a voltage divider operated by a user to output aplurality of voltage signals interpretable by the controller forexecuting the pick and play process for selecting and performing thecorresponding diffused light color temperature performance in thediffused light color temperature switching scheme.
 27. The LED securitylight according to claim 20, wherein the first external control deviceis a wireless remote control device comprising at least one wirelessexternal signal receiver electrically coupled with the controller toreceive at least one wireless external control signal, wherein the atleast one first external control signal is the at least one wirelessexternal control interpretable by the controller for activating the pickand play process to select and perform the corresponding diffused lightcolor temperature performance in the diffused light color temperatureswitching scheme.
 28. The LED security light according to claim 26,wherein the voltage divider is operated with a configuration of a slideswitch, a rotary switch, or a pull chain switch, designed with aplurality of switching positions operable by a user for selecting andperforming the corresponding diffused light color temperatureperformance from the diffused light color temperature switching scheme.29. The LED security light according to claim 20, wherein the at leastone first external control signal is an infrared light reflected from anobject entering and staying in a detection zone, wherein the firstexternal control device is an active infrared ray sensor for detectingthe infrared light reflected from the object and converting the infraredlight reflected from the object into the at least one message sensingsignal with a signal format interpretable by the controller forexecuting the pick and play process for selecting and performing thecorresponding diffused light color temperature performance from thediffused light color temperature switching scheme.
 30. The LED securitylight according to claim 20, wherein the diffused light colortemperature switching scheme comprises at least a high diffused lightcolor temperature performance and a low diffused light color temperatureperformance, wherein for performing the high diffused light colortemperature performance the second semiconductor switching device isfully conducted and the first semiconductor switching device iscompletely cut off, wherein for performing the low diffused light colortemperature performance the first semiconductor switching device isfully conducted and the second semiconductor switching device iscompletely cut off.
 31. The LED security light according to claim 20,wherein the light color temperature switching scheme comprises at leasta high diffused light color temperature performance, a low diffusedlight color temperature performance and a medium diffused light colortemperature performance, wherein for performing the high diffused lightcolor temperature performance the second semiconductor switching deviceis fully conducted and the first semiconductor switching device iscompletely cut off, wherein for performing the low diffused light colortemperature performance the first semiconductor switching device isfully conducted while the second semiconductor switching device iscompletely cut off, wherein for performing the medium diffused lightcolor temperature performance the first semiconductor switching deviceand the second semiconductor switching device are both partially andcomplementarily conducted such that the total light intensity generatedby the light-emitting unit remains essentially unchanged.
 32. The LEDsecurity light according to claim 17, wherein the low color temperatureis designed in a range between 2200 Kelvins and 3000 Kelvins, the highcolor temperature is designed in the range between 4500 Kelvins and 5000Kelvins.
 33. A method of configuring an LED lighting device with atunable diffused light color temperature, comprising: using alight-emitting unit comprising a plurality of LEDs being divided into atleast two LED loads including at least a first LED load with N numberLEDs emitting light with a low color temperature and at least a secondLED load with M number LEDs emitting light with a high colortemperature; the first LED load and the second LED load beingelectrically connected in parallel; using a light diffuser covering thefirst LED load and the second LED load to create a diffused light with adiffused light color temperature; using a switching circuitryelectrically coupled between a power supply unit and the light-emittingunit to output at least one DC power to the light-emitting unit; using afirst semiconductor switching device electrically connected between theswitching circuitry and the first LED load to control a power level of afirst electric power delivered to the first LED load; using a secondsemiconductor switching device electrically connected between theswitching circuitry and the second LED load to control the power levelof a second electric power delivered to the second LED load; using acontroller, electrically coupled with the first semiconductor switchingdevice and the second semiconductor switching device to respectivelycontrol a first conduction rate of the first semiconductor switchingdevice and a second conduction rate of the second semiconductorswitching device; using at least a first external control deviceelectrically coupled with the controller to output at least one firstexternal control signal to activate a diffused light color temperaturetuning process to select a corresponding diffused light colortemperature performance; wherein when the light-emitting unit is in aturned on state, the controller outputs the first control signal tocontrol the first conduction rate of the first semiconductor switchingdevice and the second control signal to control the second conductionrate of the second semiconductor switching device to respectivelydeliver the first electric power to the first LED load and the secondelectric power to the second LED load to generate the diffused lightwith the diffused light color temperature thru the diffuser according tothe at least one first external control signal; wherein for tuning thediffused light color temperature to a lower diffused light colortemperature, the controller upon receiving the at least one firstexternal control signal operates to increase the first conduction rateof the first semiconductor switching device to increase the firstelectric power delivered to the first LED load and simultaneouslyoperates to decrease the second conduction rate of the secondsemiconductor switching device to decrease the second electric powerdelivered to the second LED load with the same pace such that a totaldiffused light intensity remains essentially unchanged while thediffused light color temperature is accordingly adjusted to the lowerdiffused light color temperature; wherein for tuning the diffused lightcolor temperature to a higher diffused light color temperature, thecontroller upon receiving the at least one first external control signaloperates to decrease the first conduction rate of the firstsemiconductor switching device to decrease the first electric powerdelivered to the first LED load and simultaneously operates to increasethe second conduction rate of the second semiconductor switching deviceto increase the second electric power delivered to the second LED loadwith the same pace such that the total light intensity generated by thelight-emitting unit remains essentially unchanged while the diffusedlight color temperature is accordingly adjusted to the higher diffusedlight color temperature; wherein the first LED load and the second LEDload are respectively designed with a configuration of in series and/orin parallel connections such that when incorporated with a power levelsetting of the at least one DC power an electric current passing througheach LED of the first LED load and each LED of the second LED loadremains at an adequate level such that a voltage V across each LEDcomplies with an operating constraint of V_(th)<V<V_(max) featuringelectrical characteristics of a LED, where V_(th) is a threshold voltagerequired to trigger the LED to start emitting light and V_(max) is amaximum operating voltage across the LED to avoid a thermal damage orburning out of LED construction.
 34. The method of configuring an LEDlighting device with a tunable diffused light color temperatureaccording to claim 33, wherein the controller is designed with adiffused light color temperature switching scheme comprising a pluralityof different diffused light color temperature performances to berespectively activated by the at least one first external control signalgenerated by the first external control device, wherein different pairedcombinations of the first conduction rate and the second conduction raterespectively for controlling the first electric power delivered to thefirst LED load and the second electric power delivered to the second LEDload for creating different diffused light color temperatures arepreprogrammed and stored in a memory unit addressable by the controllerfor operating a pick and play process according to the at least onefirst external control signal generated by the first external controldevice for selecting a corresponding diffused light color temperatureperformance in the diffused light color temperature switching scheme.35. The method of configuring an LED lighting device with a tunablediffused light color temperature according to claim 33, wherein wheneach of the first LED load and the second LED load is configured with aplurality of LEDs electrically connected in series or sets of inparallel connected LEDs electrically connected in series, a workingvoltage across each of the first LED load and the second LED load isconfined in a domain between a minimum voltage equal to the sum of thethreshold voltages of all LEDs electrically connected in series or setsof in parallel connected LEDs electrically connected in series and amaximum voltage equal to the sum of the maximum operating voltages ofall LEDs electrically connected in series or sets of in parallelconnected LEDs electrically connected in series.
 36. The method ofconfiguring an LED lighting device with a tunable diffused light colortemperature according to claim 35, wherein when the LED has the voltageV across each LED complying with an operating constraint of 2.5volts<V_(th)<V<V_(max)<3.5 volts and the first LED load and the secondLED load are required to operate with respective operating voltagesV_(N) and V_(M) confined in domains expressed by N_(S)×2.5volts<V_(N)<N_(S)×3.5 volts and M_(S)×2.5 volts<V_(M)<M_(S)×3.5 volts,with N_(S) and M_(S) respectively denoting the numbers of seriesconnected LEDs in the first LED load and the second LED load, whereinN_(S)≤N and M_(S)≤M.
 37. The method of configuring an LED lightingdevice with a tunable diffused light color temperature according toclaim 34, wherein the at least one first external control signal is ashort power interruption signal generated by a main power switch, a pushbutton, a touch sensor or a wireless remote control device wherein apower interruption detection circuit is electrically coupled with thecontroller, wherein when the short power interruption signal is detectedby the power interruption detection circuit and converted into a messagesensing signal interpretable by the controller, the controller operatesto alternately perform the corresponding diffused light colortemperature performance in the diffused light color temperatureswitching scheme according to a prearranged sequence.
 38. The method ofconfiguring an LED lighting device with a tunable diffused light colortemperature according to claim 37, wherein when the main power switch isused for generating the short power interruption signal, the main powerswitch is turned off and turned back on within a predetermined timeinterval.
 39. The method of configuring an LED lighting device with atunable diffused light color temperature according to claim 37, whereinwhen the push button or the touch sensor is used for generating theshort power interruption signal, a signal detection circuitry isconnected to the push button switch or the touch sensor, wherein whenthe push button switch or the touch sensor is operated for a short timeinterval a voltage signal with a time length equal to the short timeinterval is transmitted to the signal detection circuitry and the signaldetection circuitry accordingly manages to transmit the short powerinterruption signal to the power interruption detection circuit forconverting to the message sensing signal interpretable by thecontroller, the controller accordingly operates to alternately performthe corresponding diffused light color temperature performance in thediffused light color temperature switching scheme according to theprearranged sequence.
 40. The method of configuring an LED lightingdevice with a tunable diffused light color temperature according toclaim 34, wherein the first external control device is a voltage divideroperated by a user to output a plurality of voltage signalsinterpretable by the controller for executing the pick and play processfor selecting and performing the corresponding diffused light colortemperature performance in the diffused light color temperatureswitching scheme.
 41. The method of configuring an LED lighting devicewith a tunable diffused light color temperature according to claim 34,wherein the first external control device is a wireless remote controldevice comprising at least one wireless external signal receiverelectrically coupled with the controller to receive at least onewireless external control signal, wherein the at least one firstexternal control signal is the at least one wireless external controlinterpretable by the controller for activating the pick and play processto select and perform the corresponding diffused light color temperatureperformance in the diffused light color temperature switching scheme.42. The method of configuring an LED lighting device with a tunablediffused light color temperature according to claim 40, wherein thevoltage divider is operated with a configuration of a slide switch, arotary switch, or a pull chain switch, designed with a plurality ofswitching positions operable by a user for selecting and performing thecorresponding diffused light color temperature performance from thediffused light color temperature switching scheme.
 43. The method ofconfiguring an LED lighting device with a tunable diffused light colortemperature according to claim 34, wherein the at least one firstexternal control signal is an infrared light reflected from an objectentering and staying in a detection zone, wherein the first externalcontrol device is an active infrared ray sensor for detecting theinfrared light reflected from the object and converting the infraredlight reflected from the object into the at least one message sensingsignal with a signal format interpretable by the controller forexecuting the pick and play process for selecting and performing thecorresponding diffused light color temperature performance from thediffused light color temperature switching scheme.
 44. The method ofconfiguring an LED lighting device with a tunable diffused light colortemperature according to claim 34, wherein the diffused light colortemperature switching scheme comprises at least a high diffused lightcolor temperature performance and a low diffused light color temperatureperformance, wherein for performing the high diffused light colortemperature performance the second semiconductor switching device isfully conducted and the first semiconductor switching device iscompletely cut off, wherein for performing the low diffused light colortemperature performance the first semiconductor switching device isfully conducted and the second semiconductor switching device iscompletely cut off.
 45. The method of configuring an LED lighting devicewith a tunable diffused light color temperature according to claim 34,wherein the diffused light color temperature switching scheme comprisesat least a high diffused light color temperature performance, a lowdiffused light color temperature performance and a medium diffused lightcolor temperature performance, wherein for performing the high diffusedlight color temperature performance the second semiconductor switchingdevice is fully conducted and the first semiconductor switching deviceis completely cut off, wherein for performing the low diffused lightcolor temperature performance the first semiconductor switching deviceis fully conducted while the second semiconductor switching device iscompletely cut off, wherein for performing the medium diffused lightcolor temperature performance the first semiconductor switching deviceand the second semiconductor switching device are both partially andcomplementarily conducted such that the total light intensity generatedby the light emitting unit remains essentially unchanged.
 46. The methodof configuring an LED lighting device with a tunable diffused lightcolor temperature according to claim 33, wherein the low colortemperature is designed in a range between 2200 Kelvins and 3000Kelvins, the high color temperature is designed in the range between4500 Kelvins and 5000 Kelvins.
 47. An LED lighting device configuredwith a tunable diffused light color temperature, comprising: alight-emitting unit comprising a plurality of LEDs divided into at leasttwo LED loads including at least a first LED load with N number LEDsemitting light with a low color temperature and at least a second LEDload with M number LEDs emitting light with a high color temperature;the first LED load and the second LED load being electrically connectedin parallel; a light diffuser covering the first LED load and the secondLED load to create a diffused light with a diffused light colortemperature; a switching circuitry electrically connected to at leastone power source to output at least one DC power to the light-emittingunit; a first semiconductor switching device electrically connectedbetween the the switching circuitry and the first LED load; a secondsemiconductor switching device electrically connected between theswitching circuitry and the second LED load; at least a first externalcontrol device to output at least one first external control signal; anda controller, electrically coupled with the first semiconductorswitching device, the second semiconductor switching device and at leastthe first external control device; wherein when the light-emitting unitis in a turned on state, the controller outputs a first control signalto control a first conduction rate of the first semiconductor switchingdevice and a second control signal to control the second conduction rateof the second semiconductor switching device to respectively deliver afirst electric power to the first LED load and a second electric powerto the second LED load to generate the diffused light with the diffusedlight color temperature thru the diffuser according to the at least onefirst external control signal; wherein for tuning the diffused lightcolor temperature to a lower diffused light color temperature, thecontroller upon receiving the at least one first external control signaloperates to increase the first conduction rate of the firstsemiconductor switching device to increase the first electric powerdelivered to the first LED load and simultaneously operates to decreasethe second conduction rate of the second semiconductor switching deviceto decrease the second electric power delivered to the second LED loadwith the same pace such that a total diffused light intensity remainsessentially unchanged while the diffused light color temperature isaccordingly adjusted to the lower diffused light color temperature;wherein for tuning the diffused light color temperature to a higherdiffused light color temperature, the controller upon receiving the atleast one first external control signal operates to decrease the firstconduction rate of the first semiconductor switching device to decreasethe first electric power delivered to the first LED load andsimultaneously operates to increase the second conduction rate of thesecond semiconductor switching device to increase the second electricpower delivered to the second LED load with the same pace such that thetotal light intensity generated by the light-emitting unit remainsessentially unchanged while the diffused light color temperature isaccordingly adjusted to the higher diffused light color temperature;wherein the first LED load and the second LED load are respectivelydesigned with a configuration of in series and/or in parallelconnections such that when incorporated with a power level setting ofthe at least one DC power an electric current passing through each LEDof the first LED load and each LED of the second LED load remains at anadequate level such that a voltage V across each LED complies with anoperating constraint of V_(th)<V<V_(max) featuring electricalcharacteristics of a LED, where V_(th) is a threshold voltage requiredto trigger the LED to start emitting light and V_(max) is a maximumoperating voltage across the LED to avoid a thermal damage or burningout of LED construction.
 48. The LED lighting device according to claim47, wherein the at least one power source is an AC power source, whereinthe switching circuitry comprises an LED driver outputting the at leastone DC power.
 49. The LED lighting device according to claim 47, whereinthe light-emitting unit is turned on by a power switch.
 50. The LEDlighting device according to claim 47, wherein the at least one powersource is a DC power source, wherein the switching circuitry comprises aconstant current circuitry outputting a constant current power.
 51. TheLED lighting device according to claim 47, wherein the light-emittingunit is turned on by a photo sensor and/or a motion sensor.
 52. The LEDlighting device according to claim 47, wherein the light-emitting unitis turned on by a wireless external control signal received from awireless remote control device, a smart phone or a smart speaker. 53.The LED lighting device according to claim 47, wherein the controller isdesigned with a diffused light color temperature switching schemecomprising a plurality of different diffused light color temperatureperformances to be respectively activated by the at least one firstexternal control signal generated by the first external control device,wherein different paired combinations of the first conduction rate andthe second conduction rate respectively for controlling the firstelectric power delivered to the first LED load and the second electricpower delivered to the second LED load for creating different diffusedlight color temperatures are preprogrammed and stored in a memory unitaddressable by the controller for operating a pick and play processaccording to the at least one first external control signal generated bythe first external control device for selecting a corresponding diffusedlight color temperature performance in the diffused light colortemperature switching scheme.
 54. The LED lighting device according toclaim 47, wherein M is equal to N.
 55. The LED lighting device accordingto claim 47, wherein M is smaller than N.
 56. The LED lighting deviceaccording to claim 53, wherein the at least one first external controlsignal is a short power interruption signal generated by a main powerswitch, a push button, a touch sensor or a wireless remote controldevice wherein a power interruption detection circuit is electricallycoupled with the controller, wherein when the short power interruptionsignal is detected by the power interruption detection circuit andconverted into a message sensing signal interpretable by the controller,the controller operates to alternately perform the correspondingdiffused light color temperature performance in the diffused light colortemperature switching scheme according to a prearranged sequence. 57.The LED lighting device according to claim 56, wherein when the mainpower switch is used for generating the short power interruption signal,the main power switch is turned off and turned back on within apredetermined time interval.
 58. The LED lighting device according toclaim 56, wherein when the push button or the touch sensor is used forgenerating the short power interruption signal, a signal detectioncircuitry is connected to the push button switch or the touch sensor,wherein when the push button switch or the touch sensor is operated fora short time interval a voltage signal with a time length equal to theshort time interval is transmitted to the signal detection circuitry andthe signal detection circuitry accordingly manages to transmit the shortpower interruption signal to the power interruption detection circuitfor converting to the message sensing signal interpretable by thecontroller, the controller accordingly operates to alternately performthe corresponding diffused light color temperature performance in thediffused light color temperature switching scheme according to theprearranged sequence.
 59. The LED lighting device according to claim 53,wherein the first external control device is a voltage divider operatedby a user to output a plurality of voltage signals interpretable by thecontroller for executing the pick and play process for selecting andperforming the corresponding diffused light color temperatureperformance in the diffused light color temperature switching scheme.60. The LED lighting device according to claim 53, wherein the firstexternal control device is a wireless remote control device comprisingat least one wireless external signal receiver electrically coupled withthe controller to receive at least one wireless external control signal,wherein the at least one first external control signal is the at leastone wireless external control interpretable by the controller foractivating the pick and play process to select and perform thecorresponding diffused light color temperature performance in thediffused light color temperature switching scheme.
 61. The LED lightingdevice according to claim 59, wherein the voltage divider is operatedwith a configuration of a slide switch, a rotary switch, or a pull chainswitch, designed with a plurality of switching positions operable by auser for selecting and performing the corresponding diffused light colortemperature performance from the diffused light color temperatureswitching scheme.
 62. The LED lighting device according to claim 53,wherein the at least one first external control signal is an infraredlight reflected from an object entering and staying in a detection zone,wherein the first external control device is an active infrared raysensor for detecting the infrared light reflected from the object andconverting the infrared light reflected from the object into the atleast one message sensing signal with a signal format interpretable bythe controller for executing the pick and play process for selecting andperforming the corresponding diffused light color temperatureperformance from the diffused light color temperature switching scheme.63. The LED lighting device according to claim 53, wherein the diffusedlight color temperature switching scheme comprises at least a highdiffused light color temperature performance and a low diffused lightcolor temperature performance, wherein for performing the high diffusedlight color temperature performance the second semiconductor switchingdevice is fully conducted and the first semiconductor switching deviceis completely cut off, wherein for performing the low diffused lightcolor temperature performance the first semiconductor switching deviceis fully conducted and the second semiconductor switching device iscompletely cut off.
 64. The LED lighting device according to claim 53,wherein the light color temperature switching scheme comprises at leasta high diffused light color temperature performance, at least a mediumdiffused light color temperature performance and at least a low diffusedlight color temperature performance wherein for performing the highdiffused light color temperature performance the second semiconductorswitching device is fully conducted and the first semiconductorswitching device is completely cut off, wherein for performing themedium diffused light color temperature the first semiconductorswitching device and the second semiconductor switching device arepartially and complementarily conducted such that the total lightintensity generated by the light-emitting unit remains essentiallyunchanged, wherein for performing the low diffused light colortemperature performance the first semiconductor switching device isfully conducted while the second semiconductor switching device iscompletely cut off.
 65. The LED lighting device according to claim 64,wherein the controller is further designed with a free running processto operate a free running performance of the diffused light colortemperature switching scheme, wherein a second external control deviceis designed to output a second external control signal to activate thefree running process, wherein the controller manages to operate the freerunning process to gradually rotate a running pick and play of thediffused light color temperature switching scheme, wherein the freerunning process operates to perform the low diffused light colortemperature performance first for a predetermined short time interval,and then is switched to perform the medium diffused light colortemperature performance for the predetermined short time interval, andthen is switched to perform the high diffused light color temperatureperformance for the predetermined short time interval to complete a freerunning cycle, the free running cycle continues till the second externalcontrol signal is ceased or till the second external control deviceoutputs another second external control signal to end the free runningprocess.
 66. The LED lighting device according to claim 47, wherein thelow color temperature is designed in a range between 2200 Kelvins and3000 Kelvins, the high color temperature is designed in the rangebetween 4500 Kelvins and 5000 Kelvins.
 67. The LED lighting deviceaccording to claim 47, whether the LED lighting device is an LED lightbulb, an LED recessed light, an LED ceiling light, an LED pendant light,an LED wall light, an LED under cabinet light, a ceiling fan light kit,a portable LED lamp or any other LED lamp for indoor or outdoorapplication.
 68. The method of configuring an LED lighting device with atunable diffused light color temperature according to claim 34, whereinthe at least one external control device is a push button or a touchsensor, wherein when the push button or touch pad is operated for ashort period of time, a short voltage signal with a signal time lengthequal to the time length the push button or touch sensor is contacted,wherein the controller accordingly operates to activate the pick andplay process to alternately perform the diffused light color temperaturein the diffused light color temperature switching scheme according to aprearranged sequence.
 69. The LED lighting device according to claim 53,wherein the at least one external control device is a push button or atouch sensor, wherein when the push button or touch pad is operated fora short period of time, a short voltage signal with a signal time lengthequal to the time length the push button or touch sensor beingcontacted, wherein the controller accordingly operates to activate thepick and play process to alternately perform the diffused light colortemperature in the diffused light color temperature switching schemeaccording to a prearranged sequence.